Heating system for airplanes



Jan. 16, 1940. VAN DAAM 2,187,506

HEATING SYSTEM FOR AIRPLANES Filed Aug. 19., 1957' IzUenZor': Gerriif ln/fiaarm Patented Jan. 10, 1940 UNITED STATES PATENT OFFICE 1 Claim.

The invention relates to improved means for heating the outer surfaces of airplanes.

The object of the invention is to provide improved means for imparting heat to the outer surfaces, or the surfaces of an airplane which are exposed to the weather and which are most liable to accumulate ice or snow, in order to reduce o prevent such accumulations.

The invention comprises simple, and eflicient means for distributing heated air to and through inner spaces of the wings, ailerons, and other controls, or parts, and also upon the outer surfaces of some, in order to communicate to the to accomplish the desired purpose.

The invention comprises means for utilizing the motion of the plane for introducing air to,

and through a heating zone, with means for distributing the heated air, from said heating zone, to the. parts or surfaces of the plane structure to which it is desirable to impart the required temperature.

The invention comprises valve-controlled passages, for delivering to an air heating zone, and valve-controlledconductors or passages leading therefrom, and branching to deliver to the desired areas of said surfaces.

The invention comprises improved means for providing the necessary heat to the air passing through the heating zone, free from any danger of causing fire.

The invention comprises means for supplementing the effect of the plane movement for causing air to flow through the heating zone. Said means also adapted to cause said air movement without depending upon said plane movement. Said air movement, being subject to arbitrary control, with respect to pressure, volume and velocity.

The invention also comprises improved electric heating elements, having no parts of the resistance exposed to the atmosphere.

The invention also comprises improved details in construction, with the general object of extreme simplicity, economy, and efficiency in operation.

Referring to the drawing, which illustrates merely by way of example, preferred means for effecting the objects of the invention, in which- Fig. l is a plan view.

Fig. 2 is a side elevation.

Fig. 3 'is a fragmentary plan of a part of the wing with part of the upper wall cut away, the view being on an enlarged scale.

Fig. 4 is a vertical sectionon line 4-4 of Fig.

Fig. 5 is a fragmentary horizontal section on line 5--5 of Fig. 2, on an enlarged scale.

Fig. 6 is a plan view of an improved heating element, on an enlarged scale, part of the outer casing broken away.

Fig. 7 is a cross-section of same.

Fig. 8 is a side elevation of same.

Fig. 9 shows a scheme for alternative circuit connection of the heater.

Similar numerals refer throughout the several views.

In the drawing the invention is shown, simply by way of example, as applied to a monoplane, in which it indicates the fuselage, I! the engine, I3 the propeller, and M the wing. Obviously the invention herein described and claimed will apply equally to biplanes, varying widely in shape and design. On either side of the front end or nose I5 of the fuselage, preferably to the rear of the engine l2, are provided flaring openings [6 connected by passages H to a centrally disposed chamber or port l8, which forms a heating zone, and is preferably located centrally or co-axial with the fuselage.

Associated with this chamber 18, is provided a suitable air heater, indicated in the drawing as an electrical resistance heater I9.

Other forms of heater may obviously be used in connection with the other novel features of my device herein described.

Associated with this heater, is provided an to similar parts electrically driven fan 20, adapted to propel the air from the central chamber or zone 18 to and through the pipes or conductors 2|, preferably approximately co-extens'ive with and flanking the fuselage ll.

These flanking conductors 2| are especially arranged to convey heated air to the various controls 22 to 25, and may also be utilized to impart or furnish heat to the fuselage or to such other parts or surfaces as may be required.

The forward pair of'struts or supports 26 of the wing ll, in the present example, are provided with passages 21 for conducting heated air from the flanking conductors 2| to a pipe or conductor 28 extending transversely of the plane travel.

It will of course be understood that other conductors or piping may be used to deliver the heated air from the heating zone to said conductor 28.

This conductor 28 is positioned within the This conductor 28 is provided with discharge vents 3|! evenly spaced apart and discharging against the inner surface of the cambered front wall 29 of the wing, in substantially horizontal lines.

Branch pipes 3| extend from the conductor 28 or from the struts 26 to the ailerons 32, and deliver through suitably iointed connections, to the interior of said ailerons.

Both the wing l4 and the ailerons 32 have air discharge ports 33 and 34 respectively, along theirtrailing edges.

Under someconditions the direct heating of the interior of the ailerons, by means of the vbranch pipes 3|, may be dispensed with, since the heated air discharging from vents or ports 33 of'the wing against the cambered front edges and over the tops of the ailerons, will suffice to prevent ice accumulation on said front edges or other critical parts of said ailerons.

The electrical heater l9, associated with chamber or heating zone l8, may in some cases, be of conventional type, provided the same is effective to impart the required degree of heat to the air passing therethrough.

In case however, where the plane is constructed of material other than metal, and the usual exposed or-bare resistance wires are prohibited, I provide heating units, comprising the resistance hermetically sealed in casings of non-combustible material, preferably metal, which are effectively insulated from the resistance wires. Such a heating unit or element is shown in Figs. 6,? and 8. The unit 35 comprises a grid 36, or woven fabric composed of warp and weft, one being strands of electrical resistance, the other being strands or cords of asbestos or the like. This grid is enclosed in the metal casing 31, but insulated from said casing, which is hermetically sealed. Such electrical units are in substantial accordance with the U. S. patents to Stranszky No. 1,833,761 and No. 1,869,629. These units may be made of very light metal and-of any desired shape or size, and may be assembled in the heating zone or chamber in any desired number and arrangement. By suitable wiring and switching, the entire set of units may be brought into circuit, or they may be connected selectively in sets so as to control the degree of heat to meet the conditions existing at any specific time.

The method of wiring these units 35, in sets or groups with switching means for bringing some or all of the units into the electric circuit is indicated in Fig. 9. v

The generator, such as 42 in Fig. 9. may be operated in a number of ways for example by taking power from the propeller engine or by its own air motor.

The storage battery may be used as a supplement, or alternative.

It will be understood that, by the use of suitable, valve-controlled conductors from the heating zone, the desired amount of heat will be imparted to the critical surfaces or parts of the plane, which may be indicated.

A distinguishing feature or characteristic of this invention is that the air is introduced to a heating zone within and near the front end of the fuselage, normally due to the travel of the plane, which causes the air to enter said heating zone with a substantial pressure. The fan 20 is adapted to supplement the natural movement and pressure of the air to and through said heating zone, or the fan may be substituted to provide the energy for such air movement in case of need. The motor of the fan is adapted to be connected with an available electric circuit, such as a storage battery or a generator circuit. A clutch 4| may also be provided to connect the fan with the engine shaft in case of need, so that it will be seen that the air pressure is always under control. Obviously when the plane is at rest. or the engine is not running, the fan can be operated by a battery or a generator current.

After receiving heat from the heater in the heating zone, the air may be delivered directly into the hollow spaces within the wing, ailerons, etc. The heated air delivered to the interior of the wing is discharged directly against the inner surface of the cambered front wall of the wing. As this air is free from deleterious gases, and is usually only moderately heated, itmay safely be delivered directly into the space between the walls of the wing and ailerons, no matter of what material the walls are composed.- Insulation for the conductors, especially 2| and 26, may be used to conserve the heat during its travel to point of ultimate delivery. Suitable valves are preferably provided in all conductors.

For example valves 39 are shown for controliinl the passages leading to the heating zone, while valve l0 controls the distributingpipes or conductors. Obviously the flanking openings l8, or the passages ll may be entirely closed when said heated air is not required.

The switch controlled system of wiring the heating elements, as shown in Fig. 9, provides effective means to vary the efficiency of heat transfer required to meet temperature or atmospheric conditions.

In view of the simple method of application, and means for concentrating the heat at critical points, a remarkably moderate temperature only is required.

In operation:

In accordance with the means and method of operation, above described, it will be seen that air is delivered to a heating zone in the forward part of the fuselage subject to suitable controls to secure and maintain the volume and velocity or pressure required.

The air heating element, in the heating zone is so positioned and controlled as to impart to the air passing therethrough, the required degree of temperature.

By providing suitable passages from the heating zone, and by providing valve controls for these passages, the heated air is delivered directly to the critical parts or surfaces of the plane.

Bycritical parts or surfaces is meant such parts or surfaces of the plane that are most liable to accumulate ice to a dangerous degree.

These critical parts or surfaces especially include the cambered front edges of the wings. ailerons, rudders and the like, the leading edges of the propeller toward the axis and especially the hub. Air vents, wires and struts should also be kept free from ice accumulation.

- It will be obvious that by delivering the heated air to such parts and surfaces. and by concentrating the heat at especially critical points by.

perature, pressure, volume. or velocity, both economy and remarkable efliciency may be secured.

Various temperature indicating devices are known, for informing the operator as to the temperature or ice condition of said critical surfaces and parts, so that he may be guided in utilizing the controls for correcting said temperatures at the required or more urgent points.

All of the specific details of means for delivering the heated air to the several parts and surfaces are not described herein. Some are made the subject of further application for patent.

It is thought however that the application as shown anddescribed in this specification will be sufficient to illustrate the general character of the present invention. I

It should be noted that the air pipes or conductors maybe made of very light metal. These pipes are preferably thoroughly insulated to prevent loss of heat by the air, during its passage from the heating zone to the critical point of discharge. This especially enables the operator to conserve his supply of heated air, for delivery only at the points required. It follows that the required total amount of heated air, and the temperature of the same, will always be safely within the limits of maximum production.

For example the volume and velocity of the air delivered from the heating zone directly to the inner wall surface of the cambered front edge of the wall, will not be great, nor needthe temperature be excessive to keep the said wall sufficiently warm to prevent ice accumulation.

For this reason, the devices herein disclosed provide efficient-and economical means for securing the object desired.

The means above described comprise a heating zone associated with a heater and blower, valvecontrolled air supply pipes leading thereto, and valve-controlled distributing pipes leading therefrom. The valve controls are placed conveniently for the operator. tremely simple and adds little weight and occupies small space in the standard plane.

What I claim is:

In a heating system for airplanes, the combination of an air heating zone, air heating means associated with said zone, means delivering air thereto, air distributing passages leading therefrom, said distributing passages including a conduit provided with spaced apart vents for dis charging jets of heated air horizontally and directly againstthe inner surface of the front came bered' wall of the wing, said wing provided with discharge vents in its trailing edge for delivering jets of heated air directly against the outer surface of the cambered front wall of the ailerons.

GERRIT VAN DAAM.

The whole system is ex- 

